Gimme a “D’’ for Tom Morris’ wan summer-school comedy — getting an undeserved token theatrical run concurrent with its debut on iTunes — that wavers between extreme silliness and unbearable earnestness.

Three writers contrived this story of a teenage tennis star (Chris Sheffield) who’s just won a scholarship — but lies to his parents (a mugging Larry Miller as his mayor dad, and Janeane Garofalo as his long-suffering alcoholic spouse) about having a summer job while he takes classes so he can actually graduate from high school.

“General Education’’ isn’t particularly funny or touching, but the cast gives the material more effort than it’s worth, especially Maiara Walsh as the teen’s love interest and McKaley Miller as his aspiring-mime sister. Skylan Brooks, as his stereotypical black sidekick, has the most thankless role.